Yarn feeding device

ABSTRACT

The invention relates to a yarn feeding device with a stationary storage drum and an adjustable yarn pitch. The yarn feeding device comprises a motor housing, a drive shaft of a winding element and a storage drum. Said storage drum consists of meshing finger-shaped cages. The finger-shaped advance cage has an advance bushing that is eccentric and skew with respect to the drive shaft. A backturn detent for the take-up element is mounted in said advance cage. The backturn detent is furthermore interposed between the finger-shaped advance cage and the drive shaft.

FIELD OF THE INVENTION

The invention relates to a yarn feeding device.

BACKGROUND OF THE INVENTION

Yarn feeding devices operating with adjustable yarn separation and abackturn detent for the winding element are known in practice by priornotorious use and e.g. disclosed in WO/A-99/14149. Such yarn feedingdevices predominantly are used for processing special yarn materials,e.g. for supplying the weft yarn when weaving filtering or bossingfabric webs for paper or cardboard production. Due to the elasticity orrigidity of the yarn material or due to certain mechanical conditions atendency of a backturning motion of the winding element occurs counterto the winding on direction when the winding element stops. This mightresult in the formation of loops or kinks in the yarn or might lead tooverlaps between the yarn windings on the storage drum and finally inoperation failures. The backturn detent is provided between the motorhousing and the drive shaft or in the supporting bearing of thestationary rod cage and prevents this undesirable backturn motion of thewinding element. The yarn separation, i.e. the intermediate distancebetween respective two adjacent yarn windings on the storage drum insuch cases with delicate yarn material is an extremely important measureto properly control the yarn. As the magnitude of yarn separation(pitch) is not the same for all yarn qualities and yarn types but isdependent on each yarn type or each yarn material, respectively, andindividually depends on different factors, the magnitude of the yarnseparation has to be adjusted in order to achieve optimum conditions forthe respective yarn being processed. The yarn separation results from anadvance motion in a direction oriented to the withdrawal end of thestorage drum, which advance motion is imparted on to the yarn windingson the storage drum. For that function it is a common principle torotate by the drive shaft an eccentric and skew cylinder inside theadvance rod cage. The advance rod cage of the stationary storage drum issupported rotatably on said cylinder. The rotation of said cylindergenerates a wobbling motion of the advance rod cage. Thanks to thewobbling motion the rods of the advance rod cage first move outwardlybeyond the rods of the supporting rod cage, simultaneously are movedforward relative to the winding on location of the yarn, and finallyre-enter inwardly behind the rods of the support rod cage, reverse theirmotion direction and return to their home position. In order to vary themagnitude of the yarn separation either the radial plane of the maximumeccentricity is rotated about the axis of the drive shaft relative tothe plane of the skew inclination of the cylinder to vary the phaseoffset between those two radial planes, or the magnitude of the skewnessposition is varied at a given phase offset between the two radialplanes. In case of the first, technically simpler method, a bushingcarrying the skew cylinder surface is rotated on an eccentric elementwhich either is provided on the drive shaft or even is formed at thedrive shaft. In this case, for adjustments the bushing is held againstrotation from outside and the drive shaft is rotated inside with thehelp of the winding element and in one or the other rotationaldirections. However, the mentioned backturn there only allows a rotationof the drive shaft in one direction of rotation, namely in the windingon direction. For this reason an adjustment of the yarn separation inthe locked direction of rotation cannot be carried out by simplyrotating the driving shaft by means of the winding element.

It is an object of the invention to provide a yarn feeding device of thekind as disclosed at the beginning at which the yarn separation despitethe presence of a backturn detent can be increased or decreased bysimply rotating the driving shaft.

As intended, the backturn detent prevents the undesired backturningmotion of the winding element since the driving shaft is blocked inbackturning direction by the backturn detent and the advance rod cageinside the stationary storage drum. According to this the desired safetyeffect of the backturn detent is reliably achieved. As for theadjustment of the yarn separation the advance rod cage has to be heldwhile the drive shaft is rotated in one or the other direction ofrotation. The locking action of the backturn detent in backturnrotational direction optionally even can be used to provide the relativerotation between the planes of the skew inclination position and theeccentricity. For that reason it is comfortably possible to increase ordecrease the yarn separation despite the action of the backturn detentand only by rotating the drive shaft, e.g. by hand, and with the help ofthe winding element in the respectively required direction. Extremelycomfortable and quick adjustments even can be carried out in the blockeddirection of rotation without an auxiliary tool just with the help ofthe backturn detent.

The backturn detent can be provided in the advance support in astructurally simple and space saving manner.

As relative rotational movements between the drive shaft and thestationary advance rod cage occur between the inner race and the outerrace of a usual ball bearing or between the bearing surfaces of a plainbearing, it is expedient to provide the backturn detent between theraces or between the bearing surfaces, respectively. In this caseexpediently a conventionally available bearing just containing thebackturn detent can be used. The backturn detent can be equipped bylocking elements, similar to the free wheel assembly of a bicycledriving hub, which locking elements engage automatically only in case ofor prior to the not desired rotational motion. As a consequence thebackturn detent can be made as a rotational freewheel device lockingautomatically in one rotational direction or as a overtaking rotationalclutch locking automatically in one rotational direction. Alternatively,the backturn detent may be located between the advance bearing and thedrive shaft such that the advance bearing is supported by the backturndetent on the drive shaft or the adjustable element of the yarnseparation mechanism respectively.

As a further alternative the backturn detent may be provided parallel tothe advance bearing and at a side of the latter. The locking effect isimparted between the bearing races or the bearing surfaces,respectively, or directly between the element and the advance rod cage,which element is provided for rotational adjustment on the drive shaft.

For a comfortable and gradual adjustment of the yarn separation the axisof eccentricity and the axis of the skew inclination are adjustable inrelation to each other and/or relative to the axis of the drive shaft.

The axis of the eccentricity and the skew inclination axis are adjustedin relation to each other in rotational direction of the drive shaft ineach sense of rotation, in order to allow to use a rotational motion ofthe drive shaft for the adjustment, which rotational motion may beimparted manually. In this it is expedient to integrate the axis ofeccentricity into the drive shaft and to constitute the axis of the skewinclination by a separate element mounted on the drive shaft for itsrotational adjustments.

In a plain bearing even the bearing surfaces could be located skew oreccentrically with respect to the axis of the drive shaft. In this casethe inner bearing sleeve is constituting the element necessary for theadjustment of the yarn separation, which element they can be rotatedrelative to the drive shaft.

The phase offset between the skew inclination position and theeccentricity is varied by relative rotational adjustments such that anincrease or decrease or even a complete nullification of the yarnseparation results.

In a structurally simple way a bushing is provided at a carrying surfaceof the drive shaft such that the bushing can be rotated on the driveshaft and can be fixed in the respective desired rotational position.The bushing constitutes an element of the yarn separation adjusting yarnmechanism which element can be adjusted by rotation. In this case eitherthe carrying surface of the drive shaft or the counterstay surface ofthe bushing may be formed eccentrically. The respective other of bothsurfaces in this case then is located in a skew inclined position.

Expediently, the advance bearing is provided on the bushing without thepossibility to be rotated. Furthermore, a rotational locking socket isprovided for engagement of an adjustment tool in order to hold thebushing in case of an adjustment of the yarn separation and when thedrive shaft is rotated relative to the bushing by means of the windingelement.

An adjustable friction clutch between the bushing and the drive shaftallows a comfortable and simple handling. The friction connection of thefriction clutch only needs to be strong enough so that the bushingreliably is taken with in case of normal rotation of the drive shaft,and just so strong that the backturn locking force is unable to overcomethe friction force of the friction clutch.

At least two axially spaced apart roller bearings or plain bearings areprovided to achieve a stable support of the advance rod cage. Thebackturn detent, however, only needs to be provided in one of bothbearings. If desired, however, each bearing of the advance support couldbe equipped by backturn detents.

A simple handling of the yarn feeding device in case of an adjustment ofthe yarn separation is possible, if the adjustment tool is constitutedby an on-board pin adjustable in the front end of the storage drumbetween an engaging position in the rotation locking socket and apassive position. In case that the pin is pre-loaded by a spring, e.g.towards its passive position, an adjustment process can be carried outeasily, because the pin only need to be pressed counter to the springforce into its engaging position, before the drive shaft is rotatedaccordingly. Later, by spring force, the pin automatically returns intoits passive position.

In order to avoid an excessive adjustment expediently a stop arrangementought to be provided for limiting the relative rotational adjustmentstroke of the bushing on the drive shaft.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the invention will be described with the help of thedrawing. In the drawing:

FIG. 1 is a longitudinal axial section of components of a yarn feedingdevice, the yarn feeding device including an adjustable yarn separationand backturn detent.

DETAILED DESCRIPTION

A yarn feeding device F in FIG. 1 has a motor housing 1 containing anelectromotor 2 driving a drive shaft W about an axis X in one selecteddirection of rotation. A winding element 3 is provided at drive shaft W,e.g. a winding tube, terminating outside of motor housing 1 andextending obliquely outwards from hollow drive shaft W. Winding element3 in this case is incorporated into a so-called winding disk 4 which iscarried by drive shaft W and is located between motor housing 1 and astorage drum 6 which storage drum is supported via the drive shaft W atmotor housing 1. Drive shaft W functions as the carrier of storage drum6 and has, for this purpose, a coaxial extension 5.

Storage drum 6 is combined from two interengaging rod cages, namely of asupporting rod cage 7 having axial rods 8 spaced apart incircumferential direction, and an advance rod cage 28 having axial rods9 respectively provided in the interspaces between rods 8. Support rodcage 7 has a stationary front end 24 and is located on a hub 10 which issupported rotatably on the extension 5 by a support bearing 11 (e.g. tworoller bearings) coaxially with axis X of drive shaft W.

To hinder storage drum 6 against rotation with the rotating drive shaftW, co-operating permanent magnets 12, 13, as well known, are provided inthe motor housing 1 and in hub 10, respectively (stationary storagedrum).

The rods 9 of the advance rod cage 28 are provided at a common hub 14.The hub 14 is supported by a bushing B rotatably seated on drive shaft Win an advance bearing 15 provided eccentrically and skew or inclinedrelative to the axis X of drive shaft W. The bushing B is seated on asupport surface 16 which is cylindrical and located eccentricallyrelative to the axis X. Cylindrical support surface 16 is formed onextension 5 or is constituted by a not shown member provided onextension 5. An eccenter axis X1 of support surface 16 is distanced by ameasure e from axis X. Another cylindrical support surface 17 is formedat the periphery of bushing B and is skew and inclined relative to axesX and X1 (indicated by the dash dotted inclination axis X2).

In the drawing the eccenter axis X1 and the inclined axis X2, forillustration purposes only, are shown in the drawing plane. In order toachieve the yarn separation Z between the yarn windings of the yarn Ywound by winding element 3 onto storage drum 6, however, a phase offsetin rotational direction of drive shaft W has to be provided between theplane containing the axes X, X1 and the plane containing the inclinationaxis X2. In order to increase, decrease or completely nullify the yarnseparation Z the above-mentioned phase offset between the inclinationaxis X2 and the eccenter X1 is to be varied in the respective directionof rotation. A friction clutch R is provided between the bushing B andthe drive shaft W, e.g. in the form of a spring package 19 loading thefree front end of the bushing B which spring package 19 is pre-loaded bya tensioning screw 18 inserted into the set back free end of the driveshaft W. The spring package 19 couples the bushing B with apredetermined rotation resistance with the drive shaft W.

Furthermore, a rotation-locking socket 21 is provided in the advancebearing 15, e.g. at a ring flange 20 which may, e.g., be coupled to thebushing B in rotational direction.

An on-board adjustment tool 22 is located in the stationary front end 24of storage drum 6. The adjustment tool 22 has the form of a pin whichcan be brought into an engaging position into rotation locking socket 21counter to spring force from the shown passive position. In the shownembodiment the advance bearing 15 consists of two axially spaced apartroller bearings. Of the roller bearings the roller bearing 29 facingtowards the free end of the drive shaft W is equipped with a backturndetent D. The roller bearing 29 comprises an inner race 25 and an outerrace 26 and roller bodies 27 located therebetween. The backturn detent Dis functionally integrated between the inner race and the outer race 25,26. Alternatively, the advance bearing 15 instead could include one ortwo plain bearings having co-operating slide surfaces.

Even though the detail structure of the backturn detent D is not shown,it is to be noted that it is a freely available rotational freewheel oran overtake rotational clutch (sprag clutch) containing locking elementswhich automatically move into a locking engagement when a rotation tendsto occur in the undesired rotational direction. In the shown embodimentthe backturn detent D is integrated into the advance bearing 15. It is,however, possible to incorporate the backturn detent into the rollerbearing shown in FIG. 1 on the left side, or even to equip both rollerbearings with a respective backturn detent. Furthermore, it is possible,to provide the backturn detent D between the inner race 25 and thebushing B, or to provide it parallel to the respective bearing and atthe side of the same.

Finally, a stop assembly 30 is provided between the bushing B and thedrive shaft W for limiting the rotational stroke of the bushing Brelative to drive shaft W.

In operation of the yarn feeding device F the rotating winding element 3is supplying the yarn Y onto the storage drum 6. Due to the skew andeccentric support surface 17 of the bushing B rotating with the driveshaft W the inner race 25 is carrying out a rotating wobbling motion. Asthe stationary support rod cage 7 is hindered by the co-operatingpermanent magnets 12, 13 to rotate with the drive shaft, also theadvance rod cage 28 is hindered by the mutually inter-engaging rods 8and 9 from rotating with the drive shaft.

Between the inner race 25 and the outer race 26 a rotational motion cantake place in only one direction of rotation. At the same time tiltingmotions derived from the wobbling motion of the inner race 25 aretransmitted into the rods 9 which effect the advance motion of the yarnwindings and by this produces the adjusted yarn separation Z.

If the electromotor 2 is stopped a tendency of a backturn motion of thewinding element 3 counter to the former winding on direction can occur,e.g. due to tension in the yarn Y. However, the backturn detent D thenis coupling the inner race 25 to the outer race 26 and blocks the driveshaft W in this undesired direction of rotation against the hub 14 ofthe advance rod cage 28. A backturn motion is prevented.

In case that the yarn separation Z is to be varied, i.e. is to beincreased, decreased or completely to be nullified, first theelectromotor 2 is stopped. Then the winding disk 4 is rotated manuallyand at the same time a frontally located button is pressed to insert thetool 22 into the rotation locking socket 21. As a consequence of thefriction connection of the friction clutch R the drive shaft W or thewinding disk 4, respectively, can no longer be rotated freely. As soonas the friction resistance of the friction clutch R is overcome,however, the support surface 16 can be rotated with the drive shaft Wwithin the bushing B, while the bushing B is locked by the tool 22.Within the rotational stroke determined by the stopping assembly 30 therespective desired adjustment of the yarn separation Z can be carriedout. As soon as the tool 22 is set free, or the button is released whichis provided in the front side 24 to actuate the tool 22, respectively,the return spring moves the tool 22 back into the shown passiveposition, preferably assisted by a slight manual rotational movement ofthe winding disk 4 in one or the other direction of rotation. Then theyarn feeding device F again is ready to operate.

As an alternative for the shown adjustment tool 22 a separate adjustmenttool could be inserted from outside between the interengaging rods 8, 9or even through one of the rods into a then modified rotation lockingsocket 21 to allow to hold the bushing B against rotation. Basically,the backturn detent D is active in one direction of rotation of thedrive shaft W and parallel to the adjustment tool 22. This has theeffect that also the backturn detent D supports the bushing B in thisdirection of rotation against rotation at advance rod cage 28 and, inturn, at the storage drum 6. In case that a desired adjustment of theyarn separation Z needs only a rotational movement of the drive shaft Win the rotational direction locked by the backturn detent D, thenadjustment tool 22 does not need to be actuated. Such adjustments can becarried out by using the locking function of the backturn detent Dinstead.

In case that the operational direction of rotation of the windingelement 3 is to be reversed, either the roller bearing 29 containing thebackturn detent D has to be reversed, or a respective roller bearing 29is to be mounted containing a backturn detent acting in the oppositedirection of rotation.

What is claimed is:
 1. Yarn feeding device comprising a stationarystorage drum and operating with an adjustable yarn separation, having amotor housing for supporting a drive shaft of a winding element andforming a carrier for said storage drum, said storage drum comprisingtwo interengaging rod cages, one of which being a support rod cagecomprising a support bearing coaxial to said drive shaft, the other ofwhich being an advance rod cage comprising an advance bearing situatedeccentrically and skewed relative to said drive shaft, and furthercomprising a backturn detent for said winding element, wherein saidbackturn detent is located between said advance rod cage and said driveshaft.
 2. Yarn feeding device as in claim 1, wherein said backturndetent is provided in said advance bearing.
 3. Yarn feeding device as inclaim 1, wherein said advance bearing includes at least one rollerbearing having an outer race and an inner race, and that said backturndetent is provided between the outer race and the inner race or betweenthe bearing surfaces, respectively.
 4. Yarn feeding device as in claim1, wherein said backturn detent is located between the advance bearingand the drive shaft.
 5. Yarn feeding device as in claim 1, wherein saidbackturn detent is located parallel to said advance bearing and at theside of the same.
 6. Yarn feeding device as in claim 1, wherein saidbackturn detent is a rotational freewheel automatically locking in onedirection of rotation, or is an overtake rotational clutch or spragclutch.
 7. Yarn feeding device as in claim 1, wherein the skewedposition and the eccentricity of said advance bearing are defined by aneccenter axis parallel to an axis of said drive shaft and by a skew axiswhich is inclined relative to said axis of said drive shaft, and thatthe eccenter axis and said skew axis are provided adjustably relative toeach other and/or relative to said axis of said drive shaft,respectively.
 8. Yarn feeding device as in claim 7, wherein saideccenter axis and said skew axis are provided adjustably relative toeach other in the rotational direction of said drive shaft and in eachdirection of rotation.
 9. Yarn feeding device as in claim 1, wherein abushing is provided on a first skewed or eccentric support surface ofsaid drive shaft, said bushing comprising at its periphery a secondeccentric or skewed support surface for an inner race of said advancebearing, and that said bushing is provided rotatably into differentrotation positions on said drive shaft and is fixable in said rotationpositions.
 10. Yarn feeding device as in claim 9, wherein a rotationlocking socket for an adjustment tool is provided in the vicinity ofsaid advance bearing or said bushing, respectively, to temporarily locksaid bushing in relation to the rotating drive shaft for carrying outadjustments of said yarn separation.
 11. Yarn feeding device as in claim10, wherein said adjustment tool is constituted by an on-board memberwhich is adjustable within a stationary front end of said storage drumbetween a passive position and an engagement position into said rotationlocking socket, and that said member preferably is a pin which can bepushed inwardly counter to a return spring load.
 12. Yarn feeding deviceas in claim 10, wherein a stopping assembly is located between saidbushing and said drive shaft for limiting a relative adjustment strokeof said bushing.
 13. Yarn feeding device as in claim 9, wherein saidbushing is coupled to said drive shaft via an adjustable frictionclutch.
 14. Yard feeding device as in claim 1, wherein said advancebearing comprises two axially spaced apart roller bearings or plainbearings, and that said backturn detent is provided in only one of saidroller bearings or plain bearings, preferably at the bearing situatedclose to a bushing end which faces away from said motor housing.